Abstract 1221 Insights Into a New Zn Binding Protein Rv2699c in Mycobacterium tuberculosis

The tuberculosis epidemic caused by Mycobacterium tuberculosis (Mtb) remains to be a leading cause of death from a single bacterial pathogen. Knowledge of the essential proteins in Mtb involved in survival and pathogenesis is crucial for developing new drugs to combat the tuberculosis epidemic. Here, we pinpoint Rv2699c, an essential protein in Mtb, as a potential drug target. Rv2699c belongs to the DUF4193 family, which is a group of uncharacterized proteins with a shared CXXXXH motif and conserved in Actinobacteria. Previous studies suggest that Rv2699c is responsive to nutrient deprivation and redox stress. However, little is known about the structure and function of Rv2699c or other members in the DUF4193 family. In this study, we applied multiple disciplinary approaches to address this critical knowledge gap. The results from our work indicate Mtb Rv2699c is a Zn-binding protein with a unique structural fold. The four cysteines coordinating Zn are conserved in all DUF4193 members, suggesting the Zn binding site is conserved across the DUF4193 family. We have also identified two DUF4193 members in the non-pathogenic mycobacteria Mycobacterium Smegmatis (Msm). While individually dispensable, the simultaneous knockdown inhibits Msm growth under optimal conditions, emphasizing the importance of the DUF4193 members in mycobacteria. Currently we are investigating the functional partners of Rv2699c in mycobacteria, aiming to elucidate its role and the broader mechanism of action of the DUF4193 family in the survival and stress response of Actinobacteria. This work is partially supported by the National Science Foundation CAREER Award CLP 1846908 to Dr. L. Zhang's laboratory.